With a conventional imaging apparatus such as a film camera or digital camera, imaging may be performed by using camera movement of an imaging lens. “Camera movement” means lens operation (or camera operation) for changing imaging effect by breaking the basic relation between the imaging apparatus and the imaging lens in which the optical axis of the lens is perpendicular to the film plane (or imaging device plane) at the center of the imaging screen. Such operations are collectively called “camera movement”. Camera movement allows the perspective deformation of buildings or the like to be corrected, the depth of field to be controlled, and the camera's reflection in a mirror or the like to be avoided.
Camera movement can be broadly classified as shown in FIG. 35.
Camera movement includes two groups of operations. One is “displacement” including “shift” and “rise/fall”. The other includes “swing” and “tilt”. The former translates the lens plane (or the film plane/imaging device plane) while maintaining the perpendicular relation between the optical axis of the imaging lens and the film plane (or the imaging device plane). In other words, the position at which the optical axis is perpendicular to the screen is translated off the center of the screen. The latter breaks the perpendicular relation between the optical axis of the imaging lens and the film plane (or the imaging device plane). In other words, the crossed angle between the optical axis and the film plane (or the imaging device plane) are changed from 90°.
In a strict sense, only the former “displacement” corresponds to camera movement. However, in a general sense, both the former and latter are often confused and collectively called “camera movement”. Then, in the following, for convenience, “shift,” “rise/fall,” “tilt,” and “swing” are called shift movement, rise/fall movement, tilt movement, and swing movement, respectively.
These are described in more detail below. “Shift movement” means moving the optical axis of the lens (or the film plane/the imaging device plane) left or right, which is used for improving composition or correcting distortion. This operation allows changing the composition in the horizontal direction without moving the camera itself. For example, using shift movement, it is possible to perform imaging at the position shifted left or right from the center of a mirror and obtain a photograph as if taken at the center of the mirror. “Rise/fall movement” means moving the lens plane (or the film plane/the imaging device plane) up or down, which is also used for improving composition or correcting distortion as with shift movement. Rise/fall movement allows improving composition in the vertical direction without extending the elevator or leg of a tripod. When shooting looking up at a tall building with a normal camera, the far part of the building may appear smaller and tapered in a photograph. Rise/fall movement may be used for perspective control to shoot the building so that it will appear upright.
“Tilt movement” means tilting the lens plane (or the film plane/the imaging device plane) forwards or backwards with respect to the optical axis of the lens, which is used generally for changing the position of the plane of sharp focus or correcting distortion. Tilt movement allows focusing over the wide range from near field to far field even at full aperture. “Swing movement” means swinging the lens plane (or the film plane/the imaging device plane) on the axis perpendicular to the optical axis of the imaging lens, which effect is similar to that of tilt movement described above.
For example, one principle for making depth of field look deeper by manipulating the object plane using tilt movement is known as “Scheimpflug principle”. In the following, an imaging method using the Scheimpflug principle is briefly described with reference to FIG. 36. The Scheimpflug principle says that, generally, three planes extended from the object plane, the lens plane, and the imaging plane intersect atone line. Specifically, according to this principle, when an imaging device plane 400 and the principal plane of an imaging lens 401 are tilted to each other, an object plane 402 tilted so as to intersect with the imaging device plane 400 and the principal plane of the imaging lens 401 at one ridge line will be brought into sharp focus. In another recently known imaging method, the object plane is changed by adjusting the tilt angle with respect to the optical axis of the imaging lens 401.
In yet another known imaging method, for example, by using the camera movement effect according to the above method, towns and buildings are shot as if they were miniatures by adjusting the object plane, in addition to making depth of field look deeper by manipulating the object plane.
The above described imaging methods provide camera movement effects by manipulating an optical system. On the other hand, examples of imaging methods providing camera movement effects by digital processing include an imaging apparatus for performing correction by camera movement (shift movement, rise/fall movement) using image processing, without using a special lens (see JP-A-8-163428, for example), and a digital camera for converting an image that is already given a camera movement effect (for example, an image of a white board shot from an obliquely lower position) to a pseudo front image based on a manually set tilt angle and ranging data to an object (see JP-A-9-289610).
However, the technology disclosed in JP-A-8-163428 provides geometric correction similar to camera movement effect electronically with digital technology, but does not provide an imaging method corresponding to swing movement and tilt movement using image processing.
Also, the technology disclosed in JP-A-9-289610 provides a method for imaging by converting an image shot from an oblique direction to a pseudo front image, but does not provide an imaging method corresponding to swing movement and tilt movement using image processing, as in JP-A-8-163428.
In addition, obtaining by image processing an image that is given an effect equal to that of imaging with such a shallow depth of field and tilted object plane that imaging may not be performed with an actual imaging device/focal length, and obtaining by image processing an image that is given an effect equal to that of imaging with shallow depth of field have not been achieved yet.